The invention relates to a method for assembling an optical transducer device. In addition to the assembly method, this invention specifically includes a method for mounting and positioning/centering optical transducer elements in the form of pulse raster disks or pulse raster rulers on motor shafts, tool carriages and/or sliding stages as well as on vertically or horizontally movable position transducers. The present invention provides a process that protects the optical transducer element from many of the harmful effects that may be encountered during the assembly process, accurately positions the optical transducer element, wherein the optical transducer elements run edgewise through the sensor gap of a sensor/emitter element for detecting a movement or position, and adheres the optical transducer element to a hub by means of an adhesive element. The invention further relates to an optical transducer device of a suitable configuration assembled by the invention.
An optical transducer element of this type must conform to stringent requirements. It is important not to damage the optical transducer element during mounting and positioning. Furthermore, it is important to ensure accuracy in the positioning of the element, and the quality of the resolution. In addition, the ability to accurately function when there are fluctuations in temperature, pressure, and/or humidity is vital. Since large-scale production parts are involved, design concepts are required to be production-oriented, characterized by a minimal component count and by selecting components that are as simple and as fail-safe as possible. Simply put, the design of the transducer element needs to be conducive to a quick and reliable adjustment process which delivers the required precision even under difficult assembly conditions. Moreover the transducer element has to be producible in an automated manufacturing process that provides a high level of assurance.
Traditionally, pulse raster disks are generally fastened on a rotating shaft by means of a hub. Either transparent pulse raster disks or reflecting pulse raster disks are used. In the case of a transparent disk, the light beam emitted by a light source on one side of the raster disk is chopped into light pulses when the disk is rotated. The light pulses are received by a sensor element positioned on the opposite side of the pulse raster disk. In the case of the reflecting pulse raster disks, the light source and the light sensor are positioned on the same side of the pulse raster disk, usually parallel to the rotation axis, so that a scanning of the pulse raster disk and pulse raster ruler respectively can take place in the most confined space. More details on this concept are described in the utility models DE 29504883 U1 and in DE 10016959.7, to PWB Ruhlatec Industrieprodukte GmbH, which are hereby incorporated by reference as if set forth in their entirety.
In order to simplify their adjustment, optical transducer elements can be combined in an assembly unit as described for example in the utility model DE 20120932 U1 (Applicant: PWB Ruhlatec Industrieprodukte GmbH), where a sensor/emitter unit 9 (see FIG. 1 of DE 20120932 U1) in U-shape is placed on a printed circuit board 5 which is fastened to the underside of the motor 1. The pulse raster disk is positioned on the shaft-end 2 of an electric motor 1 and its outside border area runs through the gap of the U-shaped sensor/emitter unit 9. However, this arrangement suffers from installation problems that can be described as follows:
The precision of the optical transducer element depends essentially on the position accuracy of the pulse raster disk on the motor shaft relative to the position of the sensor/emitter unit on the printed circuit board. A variety of soldered joints are to be made on the printed circuit board. The properties and position accuracy of the materials within the area reached by the soldering heat are negatively affected by the high temperature. Moreover the production can only be automated through a very expensive process in which the process assurance is put in question due to a large number of production steps.